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Theorem gcdass 15245
 Description: Associative law for gcd operator. Theorem 1.4(b) in [ApostolNT] p. 16. (Contributed by Scott Fenton, 2-Apr-2014.) (Revised by Mario Carneiro, 19-Apr-2014.)
Assertion
Ref Expression
gcdass ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) gcd 𝑃) = (𝑁 gcd (𝑀 gcd 𝑃)))

Proof of Theorem gcdass
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 anass 680 . . 3 (((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0) ↔ (𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0)))
2 anass 680 . . . . . 6 (((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃) ↔ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃)))
32a1i 11 . . . . 5 (𝑥 ∈ ℤ → (((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃) ↔ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))))
43rabbiia 3180 . . . 4 {𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)} = {𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}
54supeq1i 8338 . . 3 sup({𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)}, ℝ, < ) = sup({𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}, ℝ, < )
61, 5ifbieq2i 4101 . 2 if(((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)}, ℝ, < )) = if((𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0)), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}, ℝ, < ))
7 gcdcl 15209 . . . . . 6 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ) → (𝑁 gcd 𝑀) ∈ ℕ0)
873adant3 1079 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑁 gcd 𝑀) ∈ ℕ0)
98nn0zd 11465 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑁 gcd 𝑀) ∈ ℤ)
10 simp3 1061 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → 𝑃 ∈ ℤ)
11 gcdval 15199 . . . 4 (((𝑁 gcd 𝑀) ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) gcd 𝑃) = if(((𝑁 gcd 𝑀) = 0 ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)}, ℝ, < )))
129, 10, 11syl2anc 692 . . 3 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) gcd 𝑃) = if(((𝑁 gcd 𝑀) = 0 ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)}, ℝ, < )))
13 gcdeq0 15219 . . . . . . 7 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ) → ((𝑁 gcd 𝑀) = 0 ↔ (𝑁 = 0 ∧ 𝑀 = 0)))
14133adant3 1079 . . . . . 6 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) = 0 ↔ (𝑁 = 0 ∧ 𝑀 = 0)))
1514anbi1d 740 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (((𝑁 gcd 𝑀) = 0 ∧ 𝑃 = 0) ↔ ((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0)))
1615bicomd 213 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0) ↔ ((𝑁 gcd 𝑀) = 0 ∧ 𝑃 = 0)))
17 simpr 477 . . . . . . . 8 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → 𝑥 ∈ ℤ)
18 simpl1 1062 . . . . . . . 8 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → 𝑁 ∈ ℤ)
19 simpl2 1063 . . . . . . . 8 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → 𝑀 ∈ ℤ)
20 dvdsgcdb 15243 . . . . . . . 8 ((𝑥 ∈ ℤ ∧ 𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ) → ((𝑥𝑁𝑥𝑀) ↔ 𝑥 ∥ (𝑁 gcd 𝑀)))
2117, 18, 19, 20syl3anc 1324 . . . . . . 7 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → ((𝑥𝑁𝑥𝑀) ↔ 𝑥 ∥ (𝑁 gcd 𝑀)))
2221anbi1d 740 . . . . . 6 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → (((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃) ↔ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)))
2322rabbidva 3183 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → {𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)} = {𝑥 ∈ ℤ ∣ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)})
2423supeq1d 8337 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → sup({𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)}, ℝ, < ) = sup({𝑥 ∈ ℤ ∣ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)}, ℝ, < ))
2516, 24ifbieq2d 4102 . . 3 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → if(((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)}, ℝ, < )) = if(((𝑁 gcd 𝑀) = 0 ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥 ∥ (𝑁 gcd 𝑀) ∧ 𝑥𝑃)}, ℝ, < )))
2612, 25eqtr4d 2657 . 2 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) gcd 𝑃) = if(((𝑁 = 0 ∧ 𝑀 = 0) ∧ 𝑃 = 0), 0, sup({𝑥 ∈ ℤ ∣ ((𝑥𝑁𝑥𝑀) ∧ 𝑥𝑃)}, ℝ, < )))
27 simp1 1059 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → 𝑁 ∈ ℤ)
28 gcdcl 15209 . . . . . 6 ((𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑀 gcd 𝑃) ∈ ℕ0)
29283adant1 1077 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑀 gcd 𝑃) ∈ ℕ0)
3029nn0zd 11465 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑀 gcd 𝑃) ∈ ℤ)
31 gcdval 15199 . . . 4 ((𝑁 ∈ ℤ ∧ (𝑀 gcd 𝑃) ∈ ℤ) → (𝑁 gcd (𝑀 gcd 𝑃)) = if((𝑁 = 0 ∧ (𝑀 gcd 𝑃) = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))}, ℝ, < )))
3227, 30, 31syl2anc 692 . . 3 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑁 gcd (𝑀 gcd 𝑃)) = if((𝑁 = 0 ∧ (𝑀 gcd 𝑃) = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))}, ℝ, < )))
33 gcdeq0 15219 . . . . . . 7 ((𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑀 gcd 𝑃) = 0 ↔ (𝑀 = 0 ∧ 𝑃 = 0)))
34333adant1 1077 . . . . . 6 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑀 gcd 𝑃) = 0 ↔ (𝑀 = 0 ∧ 𝑃 = 0)))
3534anbi2d 739 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 = 0 ∧ (𝑀 gcd 𝑃) = 0) ↔ (𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0))))
3635bicomd 213 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0)) ↔ (𝑁 = 0 ∧ (𝑀 gcd 𝑃) = 0)))
37 simpl3 1064 . . . . . . . 8 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → 𝑃 ∈ ℤ)
38 dvdsgcdb 15243 . . . . . . . 8 ((𝑥 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑥𝑀𝑥𝑃) ↔ 𝑥 ∥ (𝑀 gcd 𝑃)))
3917, 19, 37, 38syl3anc 1324 . . . . . . 7 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → ((𝑥𝑀𝑥𝑃) ↔ 𝑥 ∥ (𝑀 gcd 𝑃)))
4039anbi2d 739 . . . . . 6 (((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) ∧ 𝑥 ∈ ℤ) → ((𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃)) ↔ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))))
4140rabbidva 3183 . . . . 5 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → {𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))} = {𝑥 ∈ ℤ ∣ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))})
4241supeq1d 8337 . . . 4 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → sup({𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}, ℝ, < ) = sup({𝑥 ∈ ℤ ∣ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))}, ℝ, < ))
4336, 42ifbieq2d 4102 . . 3 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → if((𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0)), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}, ℝ, < )) = if((𝑁 = 0 ∧ (𝑀 gcd 𝑃) = 0), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁𝑥 ∥ (𝑀 gcd 𝑃))}, ℝ, < )))
4432, 43eqtr4d 2657 . 2 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → (𝑁 gcd (𝑀 gcd 𝑃)) = if((𝑁 = 0 ∧ (𝑀 = 0 ∧ 𝑃 = 0)), 0, sup({𝑥 ∈ ℤ ∣ (𝑥𝑁 ∧ (𝑥𝑀𝑥𝑃))}, ℝ, < )))
456, 26, 443eqtr4a 2680 1 ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑃 ∈ ℤ) → ((𝑁 gcd 𝑀) gcd 𝑃) = (𝑁 gcd (𝑀 gcd 𝑃)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 196   ∧ wa 384   ∧ w3a 1036   = wceq 1481   ∈ wcel 1988  {crab 2913  ifcif 4077   class class class wbr 4644  (class class class)co 6635  supcsup 8331  ℝcr 9920  0cc0 9921   < clt 10059  ℕ0cn0 11277  ℤcz 11362   ∥ cdvds 14964   gcd cgcd 15197 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1720  ax-4 1735  ax-5 1837  ax-6 1886  ax-7 1933  ax-8 1990  ax-9 1997  ax-10 2017  ax-11 2032  ax-12 2045  ax-13 2244  ax-ext 2600  ax-sep 4772  ax-nul 4780  ax-pow 4834  ax-pr 4897  ax-un 6934  ax-cnex 9977  ax-resscn 9978  ax-1cn 9979  ax-icn 9980  ax-addcl 9981  ax-addrcl 9982  ax-mulcl 9983  ax-mulrcl 9984  ax-mulcom 9985  ax-addass 9986  ax-mulass 9987  ax-distr 9988  ax-i2m1 9989  ax-1ne0 9990  ax-1rid 9991  ax-rnegex 9992  ax-rrecex 9993  ax-cnre 9994  ax-pre-lttri 9995  ax-pre-lttrn 9996  ax-pre-ltadd 9997  ax-pre-mulgt0 9998  ax-pre-sup 9999 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3or 1037  df-3an 1038  df-tru 1484  df-ex 1703  df-nf 1708  df-sb 1879  df-eu 2472  df-mo 2473  df-clab 2607  df-cleq 2613  df-clel 2616  df-nfc 2751  df-ne 2792  df-nel 2895  df-ral 2914  df-rex 2915  df-reu 2916  df-rmo 2917  df-rab 2918  df-v 3197  df-sbc 3430  df-csb 3527  df-dif 3570  df-un 3572  df-in 3574  df-ss 3581  df-pss 3583  df-nul 3908  df-if 4078  df-pw 4151  df-sn 4169  df-pr 4171  df-tp 4173  df-op 4175  df-uni 4428  df-iun 4513  df-br 4645  df-opab 4704  df-mpt 4721  df-tr 4744  df-id 5014  df-eprel 5019  df-po 5025  df-so 5026  df-fr 5063  df-we 5065  df-xp 5110  df-rel 5111  df-cnv 5112  df-co 5113  df-dm 5114  df-rn 5115  df-res 5116  df-ima 5117  df-pred 5668  df-ord 5714  df-on 5715  df-lim 5716  df-suc 5717  df-iota 5839  df-fun 5878  df-fn 5879  df-f 5880  df-f1 5881  df-fo 5882  df-f1o 5883  df-fv 5884  df-riota 6596  df-ov 6638  df-oprab 6639  df-mpt2 6640  df-om 7051  df-2nd 7154  df-wrecs 7392  df-recs 7453  df-rdg 7491  df-er 7727  df-en 7941  df-dom 7942  df-sdom 7943  df-sup 8333  df-inf 8334  df-pnf 10061  df-mnf 10062  df-xr 10063  df-ltxr 10064  df-le 10065  df-sub 10253  df-neg 10254  df-div 10670  df-nn 11006  df-2 11064  df-3 11065  df-n0 11278  df-z 11363  df-uz 11673  df-rp 11818  df-fl 12576  df-mod 12652  df-seq 12785  df-exp 12844  df-cj 13820  df-re 13821  df-im 13822  df-sqrt 13956  df-abs 13957  df-dvds 14965  df-gcd 15198 This theorem is referenced by:  rpmulgcd  15256  coprimeprodsq  15494  gcd32  31612  gcdabsorb  31613
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